Bigfoot Solar System - Fiberglass RV


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Old 04-18-2011, 05:16 PM   #1
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Bigfoot Solar System

Our 1986 Bigfoot had a solar power system designed for boondocking. In October 2010 vandals firebombed that trailer. I was able to salvage most of the solar equipment. We have replaced the 1986 Bigfoot with a 1991 version. Our mentor HandyBob has reinstalled the solar power system. If you are considering solar for your rig you might want to visit his somewhat vitriolic blog, which you'll find by googling HandyBob+solar. This post deals with panels. Subsequent posts will address electronics and our ability to produce and store electricity.

We have 4 each 80 watt Sharp panels. While not the most efficient panels by measure of dollars per watt, these fit on the roof nicely. Since even partial shading greatly reduces the output of an entire panel, we enjoy the ability to have at least two and usually three or four panels in full sun.

Some might say that 320 watts is overkill on such a small trailer. Those of that view have not lived the solar lifestyle. My opinion is that a system should have as many watts as the user can afford and can locate on the roof without undue shading from whatever else may already be up there. Plan for worst case, not best case scenario when it comes to incoming solar radiation [insolation].

We knew we wanted to be able to tilt for maximum insolation during winter months.The air conditioner shroud presented an obstacle to tilting. The panels have been mounted on legs that allow the aft panels to clear the shroud when tilted. To avoid one tilted panel shading another, the forward panels have identical legs to those aft so as to be parallel to the corresponding aft panel when tilted.

Held up by aluminum tilt supports, the panels tilt to starboard. With a little rearranging of hardware they can also be tilted to port. Starboard is our default direction of tilt as orienting the starboard side to face south keeps the sun off of the refrigerator, which is on the port side.

Were the starboard side panels tilted to starboard at full height the tilt supports might shade the tilted port side panels. Shorter tilt supports can be used in this case to achieve some tilting without shading. See attached picture of our previous trailer.

When not in use each full height tilt support pivots to horizontal and fits over a screw coming from a mounting foot. A stainless steel wing nut secures the support. Since the wing nut is stainless and the support aluminum, lock nuts are not necessary.

All mounts are angle aluminum custom made and HandyBob custom fit them to the roof irregularities. Anyone who owns an older Bigfoot knows what I mean by roof irregularities. The mounts are screwed to the roof after applying Proflex RV to the roof. Proflex RV was then applied to screw heads and mount edges. The panels rest on these mounts via angle aluminum attached to either side of each panel.

Panels are wired with #8 sheathed wire to a junction box under the forward port panel, and from there to the charge controller located under the dinette.
Attached Thumbnails
Two up Two flat.jpg   Panel mounting.jpg  

Roof view.jpg   Patience Panels.jpg  

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Old 04-18-2011, 06:23 PM   #2
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Tim, you are doing great work on your trailer and thank you for sharing with us. These shorty mud flaps are annoying and are on my project list. The rock guard brackets are going to go on my project list. I will try to use the current rubber latching brackets with removable support rods. Every time there is wind I close the rock guard, you have a very good idea with additional, and properly located support brackets.
Your solar cell mounts are impressive, have you measured your best charging current? Are you using MPPT controller? I donít know how your panels are connected but if you reaching high output voltage (>18V) you could benefit from MPPT controller in lieu of a commonly used PWM.
George.
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Old 04-18-2011, 06:36 PM   #3
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Thanks, George. As I mentioned, much of the credit goes to HandyBob, who seems to be able to cobble solutions from scraps. We benefited from our experience living for 9 months in the first Bigfoot 17, so when we met HandyBob for upfitting the second Bigfoot 17 we knew what we wanted.

I'll go more into the electronics in a subsequent post, but to answer your question our theoretical maximum current is 4 x 4.63, which puts us over 18 amps. I believe we had that today. We ran the fridge on 120v from 9am to 4pm and will be at 100% charge by sundown.

We use a Morningstar Tristar PWM controller. I may one day get the MPPT version of that controller, but for the moment I am satisfied.
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Old 04-20-2011, 06:55 PM   #4
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Quote:
Originally Posted by Tim D. View Post
Our 1986 Bigfoot had a solar power system designed for boondocking. In October 2010 vandals firebombed that trailer. I was able to salvage most of the solar equipment. We have replaced the 1986 Bigfoot with a 1991 version. Our mentor HandyBob has reinstalled the solar power system. If you are considering solar for your rig you might want to visit his somewhat vitriolic blog, which you'll find by googling HandyBob+solar. This post deals with panels. Subsequent posts will address electronics and our ability to produce and store electricity.

We have 4 each 80 watt Sharp panels. While not the most efficient panels by measure of dollars per watt, these fit on the roof nicely. Since even partial shading greatly reduces the output of an entire panel, we enjoy the ability to have at least two and usually three or four panels in full sun.

Some might say that 320 watts is overkill on such a small trailer. Those of that view have not lived the solar lifestyle. My opinion is that a system should have as many watts as the user can afford and can locate on the roof without undue shading from whatever else may already be up there. Plan for worst case, not best case scenario when it comes to incoming solar radiation

We knew we wanted to be able to tilt for maximum insolation during winter months.The air conditioner shroud presented an obstacle to tilting. The panels have been mounted on legs that allow the aft panels to clear the shroud when tilted. To avoid one tilted panel shading another, the forward panels have identical legs to those aft so as to be parallel to the corresponding aft panel when tilted.

Held up by aluminum tilt supports, the panels tilt to starboard. With a little rearranging of hardware they can also be tilted to port. Starboard is our default direction of tilt as orienting the starboard side to face south keeps the sun off of the refrigerator, which is on the port side.

Were the starboard side panels tilted to starboard at full height the tilt supports might shade the tilted port side panels. Shorter tilt supports can be used in this case to achieve some tilting without shading. See attached picture of our previous trailer.

When not in use each full height tilt support pivots to horizontal and fits over a screw coming from a mounting foot. A stainless steel wing nut secures the support. Since the wing nut is stainless and the support aluminum, lock nuts are not necessary.

All mounts are angle aluminum custom made and HandyBob custom fit them to the roof irregularities. Anyone who owns an older Bigfoot knows what I mean by roof irregularities. The mounts are screwed to the roof after applying Proflex RV to the roof. Proflex RV was then applied to screw heads and mount edges. The panels rest on these mounts via angle aluminum attached to either side of each panel.

Panels are wired with #8 sheathed wire to a junction box under the forward port panel, and from there to the charge controller located under the dinette.
I don't really agree with the bold statement above. I've been solar for several years now. My solar system consists of a single 65 Watt panel that when necessary comes out of the truck to charge the battery. That's worked very well for us. Others here have smaller panels that have worked well for them. The trick is NOT to increase the power available, but to decrease the power used.
Just my 2 cents worth.
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Old 04-21-2011, 12:05 PM   #5
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Sure, just two ways of looking at a solar lifestyle. I guess I should have qualified my statement. Our goal is not to minimize but to live with four or five bright lights for several hours each night, a couple of computers running several hours each day, and fans when it is warm. We do reduce our usage when the sun does not shine. I'm thinking that after four or five days of clouds in the Pacific Northwest, or among trees in the mountains that 65 watts might not do the job.
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Old 04-21-2011, 07:33 PM   #6
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the roof irregularities are sure tough with molded fiberglass non traditional shape. A few members here uses VHB tape for the panels instead of bolts. Great post, thanks for the write up. I'm looking forward to reading about how many and what type of batteries you use. Take care.
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Old 05-01-2011, 10:05 PM   #7
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Bigfoot Solar Electronics

Our friend and mentor HandyBob consulted in the planning stages and installed the solar power system documented here. The system works superbly for our needs. I assembled this guide as a reminder to myself while the information is still fresh in my mind. I thought others might like to see it. In a subsequent post Iíll mention the batteries and our solar lifestyle.

Key to solar electronics photos

1 Wiring from solar panels
2 Solar input quick disconnect
3 Morningstar Tristar TS45 charge controller
4 Shunt for Tri-metric 2025 meter
5 Common ground
6 Main DC fuse
7 DC distribution panel #1
8 250 amp inverter fuse
9 Vent holes
10 Samlex 1250-watt modified sine wave inverter
11 Umbilical cord to tow vehicle
12 DC distribution panel #2 and AC breakers
13 Transfer switch and battery charger switch
14 Shore power cable
15 Iota 30 amp battery charger
16 AC receptacle for battery charger
17 AC receptacle
18 Converter was here; now removed
19 Bogart Engineering TriMetric 2025 meter
20 Remote inverter on/off switch

Notes to solar electronics photos

1 Wiring from solar panels
#8 Sheathed landscaping wire from junction box on roof

2 Solar input fuses and quick disconnect
Very handy when working on the system or diagnosing troubles

3 Morningstar Tristar TS45 charge controller
A 45 amp controller is a bit of overkill for a system that produces less than 20 amps, but I can use it later should I get a larger trailer with more panels. A temperature sensor wire runs to the positive battery terminal to allow the controller to adjust charging voltage as battery temperature varies from 77 degrees F. The controller charges the batteries to 14.8 volts at 77 degrees F as recommended by Trojan Battery. At temperatures lower than 77 degrees F the voltage will be higher, while at higher temperatures the voltage will be lower.

4 Shunt for Tri-metric 2025 meter
The TriMetric meter measures minute voltage drops across the shunt to derive amps going in to or out of the batteries

5 Common ground

6 Main DC fuse

7 DC distribution panel #1
This panel feeds all five DC receptacles in the cabin. It also feeds the existing DC distribution panel.

8 250 amp inverter fuse

9 Vent holes
The electronics produce a fair bit of heat. These holes were drilled through the dinette pedestal to provide ventilation. An aluminum vent cover masks the holes from the outside.

10 Samlex 1250-watt modified sine wave inverter
See charge controller note. This inverter was chosen because it does not fault until 16.5 volts. At temperatures less than 77 degrees F the charge controller will allow the voltage to exceed 14.8 volts in order to fully charge the batteries. On cold days the voltage may be 15.1 or 15.2 volts. Many inverters fault at 15 volts, thus on cold days the inverter would be unusable as the batteries approach full charge. While the inverter produces AC current just fine, the cooling fan is LOUD and runs a great deal of the time. The fan may run for several minutes after a load is removed. Iíll be replacing this inverter when I can find something better.

11 Umbilical cord to tow vehicle

12 DC distribution panel #2 and AC breakers

13 Transfer switch and battery charger switch
I opted for a manual transfer switch, which selects between the batteries [inverter] and shore power as the source of AC power for AC receptacles and the air conditioner. The air conditioner will run only from shore power. When on shore power the system will still draw from the batteries for all receptacles. This way, when we are at home we can run the air conditioner on shore power but still continue to use the solar panels to power all other AC needs. Should the solar panels not be able to meet the AC and DC needs while we are at home, the batteries may become depleted. In that case the battery charger can be turned on.

14 Shore power cable

15 Iota 30 amp battery charger
Provides 3-stage battery charging

16 AC receptacle for battery charger

17 AC receptacle

18 Converter was here; now removed
HandyBob, our installer, loathes the converters installed on older RVs because they do not properly charge the house batteries. He removed our 20-year-old converter. Since our inverter is not an inverter/charger we installed a stand-alone battery charger.

19 Bogart Engineering TriMetric 2025 meter
At any time the meter will display the number of amps going in to our out of the batteries. The meter attempts to track the state of battery charge in terms of amp-hours down from full charge. The meter will display this as amp-hours down or as % of full charge. While this measure seems to be a less-than-completely-accurate, the approximation is very handy in planning electricity usage given expected future insolation.

20 Remote inverter on/off switch
As the inverter is beneath the dinette, the remote switch allows the inverter to be conveniently switched off when not in use. The no-load draw of our inverter is .3 amps.
Attached Thumbnails
Electronics Overview.jpg   Bigfoot Solar 1.jpg  

Bigfoot Solar 2.jpg   Bigfoot Solar 3.jpg  

Bigfoot Solar 4.jpg   Bigfoot Solar 5.jpg  

Bigfoot Solar 6.jpg  
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Old 05-09-2011, 06:30 PM   #8
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Tim thanx for the write-up , read the blog of Bob's and found it to be interesting and after testing and researching my own system further am in agreement with his thoughts and will be upgrading the controller and meter in my system , cheers mike
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Old 02-06-2012, 04:19 PM   #9
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Tim, ran across your post searching for another Bigfoot 17 solar installation and really appreciate your detail and referral to HandyBob. I'm inclined towards the perspective of designing the most efficient and robust solar system within a reasonable cost, with the intention of boodocking several days without hookups or a generator.

I've found solar dealers and especially RV manufacturers are not geared towards the boondocking lifestyle. Bravo! Roger
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Old 04-30-2016, 09:38 PM   #10
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Tim,

Great write-up and pictures. By chance have you drawn up a schematic of your solar powered system?

Thanks
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Old 05-02-2016, 08:20 AM   #11
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Very Nice job

Just curious, can you describe your batteries. Location and capacity. I'm envious by the way
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Old 05-02-2016, 08:56 AM   #12
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call it.....

WOW....call your trailer "the last word" in Solar Bigfoots !!!! and done by guru/legend Handy Bob himself no less...!!!! thanks for posting all that.

I'm curious about one little thing...If you do not have a converter anymore (as I do) why do you need a transfer switch?....and where does your DC power come from when you're plugged in???

In my system (very much "pedestrian" compared to yours!) the charger is plugged in all the time....if I connect to shore power the charger comes on...unplug and it's off (my charger specifically states that it is designed so it can be left on continiously...as in long term storage conditions) What I do have is a switch that shuts the solar panels off...when I plug in I shut them off so as not to "confuse" the charger.

I hope your post gets saved somewhere for future reference...it's awesome alright!
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Bigfoot Solar 4.jpg   battcharger.jpg  

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Old 05-09-2016, 05:36 PM   #13
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Thanks for the kudos; they belong to Handy Bob.

The schematic diagram for our solar power system is attached.

We use two Trojan T-145 6v batteries in series. They have the same footprint as the standard T-105 but are taller. They have about 20% more capacity than the standard. Crown Battery offers something the same.

A bit of reorganizing was required to fit the batteries on the tongue and still be able to use the fiberglass tongue cover. A welder created a dropped box for the batteries and angled the propane bottle tray forward so the bottles would be parallel to the trailer body. A tight fit but it works.

DC power comes from the batteries always. Should we wish to charge the batteries with the battery charger rather than the solar panels we hook to shore power, flip the transfer switch, and turn on the charger. The 120v outlets are dead unless we 1] turn on the inverter, or 2] hook to shore power and flip the transfer switch from "battery" to "shore".

I know people think I am nuts for having so many watts. Living on the road about 8 months per year for 8 years, we have encountered many instances where insolation is limited: Beneath trees, in canyons, cloudy days, autumn and winter. All of those watts help. Still, sometmes full sun is just a few feet from where we are forced to park.

We just finished 8 days on the Delmarva Peninsula, parked among pine trees, with clouds and rain most days. We were able to charge GPSs, VHF radios, computers, phones, run fluorescent lights as well as LEDs, use an electric kettle twice a day, and watch a 24" TV in the evenings. To maintain a reasonable state of charge [greater than 60% as a minimum] without cutting back on usage, we needed more than our 320 watts. I recently installed a through-hull fitting in the trailer body, wired into the solar disconnect at the same lug as the rooftop panels. I use it to connect two 100w flexible panels, light weight and easily stored. The addition of those two panels allowed us to live like usual even under challenging conditions.
Attached Thumbnails
20160509_173721.jpg   20160509_173220.jpg  

20160509_173258.jpg   20160430_132803.jpg  

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Old 06-16-2016, 04:27 PM   #14
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Name: Barbara
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Solar panels for new 25' Bigfoot

Hi, all! I know this thread is dated, but it is so interesting and informative that I will be saving it for future reference.

We're ready to complete our purchase order for a new 25' Bigfoot (rear twin beds!) Before we do, though, we have to figure out where to put the Fantastic Fan(s). We want to have the most flexibility to put in a big solar system, but we know we'll use the fans, too. We currently have a 17' Casita SD (and have loved it) and have used the fan a lot. We have a portable solar panel to charge the battery, but no inverter. We spend the winter months in it and we mostly boondock. I'm tired of hand grinding my coffee each morning (492 turns! ), so there WILL be a competent system installed in the Bigfoot once we get it!

So, solar installers, what do you think? One or two fans? And where should we locate them so we leave as much space for panels as possible? I don't have a roof view picture of the trailer to help me. I know the AC is over the kitchen area. Perhaps I should drive the 2 hours to look at the 25' they have on the lot to get an idea. Dither, dither, dither...arg! I don't know what to do!

We are so excited about getting our new trailer (in about 4 months, but still....)

Thanks!

Barbara
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